1. Field of the Invention
The invention herein relates to apparatus for imparting decorative surface patterns to pliable structures, primarily concrete pavements and walls.
2. Background of the Invention
Imparting of decorative patterns to the surface of newly formed concrete structures such as patios, swimming pool decks, walkways, driveways, walls and the like is a well-established industry. In many installations the pattern is formed in a surface of the wet concrete body by rolling or tamping with a machine-operated embossing pattern die. However, in numerous other installations machine embossment is either not practical or not desired. In such installations the embossment is done by a worker using a hand-held tamper. The tamper may have the pattern embossing die mounted on it so that the worker directly embosses the surface, or there may be a sheet-like pattern die laid on the wet concrete surface, and the worker then uses the tamper to tamp the back of the die to emboss the die's pattern into the surface. In either case the die is constructed such that the pattern to be imparted to the surface is formed as protrusions extending outwardly from a surface of the die. The height of the protrusions determines the depth to which the pattern is imparted to (embossed into) the concrete surface.
Hand tampers have conventionally been made of a rigid material, formerly wood but most commonly now steel. FIG. 1 illustrates a typical commercial steel tamper 2. The tamper 2 consists of a base plate 4, usually braced with ribs 6, with an integrated rigid neck 8 into which an elongated handle 10 is inserted. The handle 10 is rigidly attached to the neck 8 either by screwing or welding the handle into the neck or by having the handle and base/neck formed integrally during manufacture. These rigid tampers are difficult for workers to use comfortably and can be damaging to the concrete surface in use. If the worker does not strike the concrete surface or pattern die with the tamper held precisely perpendicular to the surface or die, the tamper base will rotate to a horizontal position as it strikes the surface or die and will jerk the handle hard against the worker's hands. The impact is often sufficient to make the worker lose a grip on the handle. Simultaneously, as the base hits the surface/die the base can push into the surface more deeply at one edge than the other, thus making the embossment uneven. In some cases tamper manufacturers have coated the steel bases with a thin elastomeric or plastic layer but that has not significantly relieved the problems, particularly the problem of the handle's impact on the worker's hands and arms.
One attempt by the prior art to alleviate these problems with tampers is illustrated in FIG. 2. In this type of tamper 12 the base 14 is made partially or entirely of an elastomeric material into which is embedded a small metal plate 16. The handle 18 is attached to the metal plate 16 usually by a bolt or screw (not shown) or the handle and plate are formed integrally and the handle/plate assembly is embedded into the tamper base 14 when the base is moulded. This type of tamper has been found to be only minimally easier to use than the conventional steel tampers. Only minimal flexibility is imparted to the handle by the embedded plate structure, so there is still substantial impact to the worker's hands and arms if the tamper is not held exactly on-line when striking the surface or die. Further, if the striking is sufficiently off-line, there is a tendency for the handle/plate assembly to tear free of the elastomeric base, thus rendering both the handle and the base unusable.
It is evident that the hand/arm impact problems result in rapid worker fatigue when using hand tampers. This in turn significantly slows the progress of embossment jobs and/or requires that a contactor hire additional tamper workers so that the workers doing the tamping can be relieved frequently.
It is therefore an object of this invention to provide for a hand tamper having a structure with a degree of flexibility sufficient to reduce or eliminate the hand/arm impacts for workers using the tamper, reduce or avoid damage to concrete surfaces from off-line strikes of the tamper, and yet have sufficient stiffness and rigidity in the structure such that good imparting of the patterns to the concrete surface is obtained consistently and quickly.